Preheat oven to 150°C/300°F, fan forced (convection) setting. Grease a 22cm/9 inch round cake pan and line the base with baking paper.
Put the chocolate and honey in a pan over very low heat, stirring often, until the chocolate is melted and the mixture smooth. If your stove doesn’t go down to a very gentle low heat I’d recommend doing this step using a double boiler so you don’t burn the chocolate.
Combine the flour and spices in a bowl and whisk to combine. Add the fruits and nuts and give everything a stir to coat them in the flour.
Add the chocolate/honey mixture to the bowl and stir well. I find clean hands easiest for this as the mixture is very stiff. Make sure everything is evenly mixed and there are no lumps of flour remaining.
Scrape the mixture into the prepared cake pan and press out gently with your hands or the back of a spoon until it’s even. Bake until golden but soft, about 45 minutes. Let it cool slightly, then run a thin knife around the edge of the pan to loosen the sides.
Cool the panforte completely in the pan, then turn it out and wrap well in aluminium foil for storage. Keep in a cool dark place and when you’re ready to serve, dust it with powdered sugar and cut into thin wedges.